Add new extracted option doctest ui test for result returning doctest

Author: GuillaumeGomez

tests/rustdoc-ui/extract-doctests-result.rs

@@ -0,0 +1,11 @@
+// Test to ensure that it generates expected output for `--output-format=doctest` command-line
+// flag.
+
+//@ compile-flags:-Z unstable-options --output-format=doctest
+//@ normalize-stdout: "tests/rustdoc-ui" -> "$$DIR"
+//@ check-pass
+
+//! ```
+//! let x = 12;
+//! Ok(())
+//! ```

tests/rustdoc-ui/extract-doctests-result.stdout

@@ -0,0 +1 @@
+{"format_version":2,"doctests":[{"file":"$DIR/extract-doctests-result.rs","line":8,"doctest_attributes":{"original":"","should_panic":false,"no_run":false,"ignore":"None","rust":true,"test_harness":false,"compile_fail":false,"standalone_crate":false,"error_codes":[],"edition":null,"added_css_classes":[],"unknown":[]},"original_code":"let x = 12;\nOk(())","doctest_code":{"crate_level":"#![allow(unused)]\n","code":"let x = 12;\nOk(())","wrapper":{"before":"fn main() { fn _inner() -> core::result::Result<(), impl core::fmt::Debug> {\n","after":"\n} _inner().unwrap() }","returns_result":true}},"name":"$DIR/extract-doctests-result.rs - (line 8)"}]}